In Exodus 3, God reveals himself to Moses through the sign of a burning bush, which miraculously is not consumed by the flames. Here is Exodus 3:1-6 in the NRSV:

Moses was keeping the flock of his father-in-law Jethro, the priest of Midian; he led his flock beyond the wilderness, and came to Horeb, the mountain of God. There the angel of the Lord appeared to him in a flame of fire out of a bush; he looked, and the bush was blazing, yet it was not consumed. Then Moses said, "I must turn aside and look at this great sight, and see why the bush is not burned up." When the Lord saw that he had turned aside to see, God called to him out of the bush, "Moses, Moses!" And he said, "Here I am." Then he said, "Come no closer! Remove the sandals from your feet, for the place on which you are standing is holy ground." He said further, "I am the God of your father, the God of Abraham, the God of Isaac, and the God of Jacob." And Moses hid his face, for he was afraid to look at God.

Why does God choose to use the sign of the burning bush, as opposed to any other miracle?

It seems to me that there should be some reason why a blazing (but not consumed) bush in the middle of the wilderness is particularly appropriate for the message that God was delivering to Moses. I was also wondering whether there is a specifically Christian interpretation of this event, given the other parallels between the Exodus and the work of Jesus.

The idea behind this consuming fire is that it is the fire of God's judgment. Just before that verse in Deuteronomy, it says not to make idols (starting in verse 24) because the God is a consuming fire. We can see pretty clearly that this fire is a picture of God's judgment and wrath.

By comparison, one thing that is striking about the image of the burning bush is that there is fire that does not consume.

This is showing us that the imagery of the burning bush is one of mercy. The consuming fire engulfs the bush, but the bush is not consumed. The judgment is brought, but mercy is shown.

Another theory is that the burning bush indicates that Israel will not be consumed by the upcoming plagues in Egypt. It was, the theory goes, a way to indicate to Moses that there will be fires and judgments but the nation will not be consumed.

A final, simpler theory is simply that God used an item that was present at that time in that location (a bush in the desert) to indicate his glory. The fire that burned was simply his glory illuminating the bush. (Fire, at that time, was the only known source of light besides the sun.)

A very good answer, though I might add that a Christian could say that that the bush is foreshadowing of the story of Christ. That punishment is given (fire = death of Christ), but this punishment is overcome (not being consumed = resurrection).
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SisyphusSep 7 '14 at 6:17

That the fire was not sustained by the bush. God's existence doesn't depend on anything nor anyone else. He is self-sustaining, and the source of all energy in the universe (I assume that this is related to God calling Himself I AM).

God is able to cleanse a living thing without destroying it - relating Moses experience to the work of Christ who makes us clean without destroying us.

Everything that God does is meaningful, significant, and purposeful to the last detail, there is no such thing as an accident or a coincidence, that would imply that God is not in control. Every detail in the Holy Scriptures is there by design.

The burning bush is a type of Christ

(Isaiah 53:2 For he shall grow up before him as a tender plant, and as a root out of a dry ground: he hath no form nor comeliness; and when we shall see him, there is no beauty that we should desire him)

The fire speaks of jealousy, or zeal, passion - same word in Hebrew.

(Deuteronomy 4:24 For the LORD thy God is a consuming fire, even a jealous God.)

And fire can also represent the effect of the Holy Spirit on the heart of a believer

(Luke 24:32 Did not our heart burn within us, while he talked with us by the way, and while he opened to us the scriptures?)

The sign is very specifically appropriate for Moses, who "lit up" with the zeal for the people of God and got "consumed", when he murdered the Egyptian, but Jesus Christ never lost control. Even when it could be said of Him "The zeal of thine house has eaten me up", it is a good thing to be passionate and jealous for the things of God.

But, Paul tells the Ephesians in ch.4:26

"Be ye angry, and sin not"

Moses had a problem controlling his anger as is seen in several instances, most notably, when he smote the rock twice with his rod contrary to the command of God, and was not allowed to enter the promised land because of it. (Numbers 20:7-11, Deuteronomy 32:48-52) God was teaching Moses something very important for the ministry that lay ahead.

Fire is indicative of purification and cleansing NOT wrath nor death for sins. Moses was sent to Save the Israelites from the error of their ways. They had gone astray and chosen to live among the Egyptians. They had chosen to follow the ways of the Egyptians. They enslaved themselves through their own 'sinful' desires for material richness-rich foods, things they thought made them happy. We know this because of their backsliding and whining in the desert. They missed the rich foods and all the other Egyptian ways of life. They chose NOT to seek God personally which is Always the wrong way.
What the bush represents is Gods consuming love that cleanses and purifies. We are not killed by the process anymore than the bush was...Gods holiness is not something to avoid or fear. We can face God and relate to Him- All can.
I am still questioning if the bush also represents eternal life since Jesus referred to it in Luke 20:37. Is Jesus indicating that eternal life has always been available? I think so. I believe it is also a representation of reincarnation but that is something I am still studying at the moment.

The flame of fire denotes the glory of God’s holiness, which excluded fallen man from direct contact with God as the tree of life (Gen. 3:24). According to Gen. 3:17-19 thorns were part of the curse that came because of man’s sin. Hence, thorns are a symbol of fallen man under the curse. The thornbush here represents Moses himself as a redeemed sinner. The flame of fire burning within the thornbush signifies that the glory of God’s holiness would burn within and upon Moses, God’s called one, even though he was a sinner under God’s curse. This was possible because of Christ’s redemption (Gen. 3:21; 4:4), which satisfied the requirements of God’s holiness and removed the curse, allowing the divine fire (the Spirit) to visit and to indwell the thornbush (the redeemed sinner), making the fire one with the thornbush (Gal. 3:13-14). The fact that the fire burned in the thornbush without consuming it indicates that God Himself, not Moses, would be the “fuel” for the burning (cf. Rom. 12:11; 2 Tim. 1:7; Phil. 4:13; Col. 1:29). Moses would be only a vessel, a channel, through which the glory of God’s holiness would be manifested (cf. 2 Cor. 4:7).

According to Deut. 33:16, the thornbush was God’s dwelling place. Since God’s corporate people are His actual dwelling place (Heb. 3:6), this implies that the thornbush refers also to God’s redeemed people as a corporate entity. After the tabernacle, a symbol of the children of Israel as God’s dwelling place, was built up, at night the cloud of God’s glory upon it had the appearance of fire (Num. 9:15-16). The fire burning upon the tabernacle signified that the people of Israel were a corporate burning thornbush. The church as God’s dwelling place is also a burning thornbush—the Triune God burning within and upon a redeemed humanity (Luke 12:49; Acts 2:3-4). Through the burning of the holy divine fire, the once cursed and redeemed thornbush is transformed to be God’s dwelling place.